1. Field of the Invention
The present invention relates to a portable display device and, more particularly, to a portable display device which is suitably used in an apparatus such as a portable television receiver, a pager, a portable telephone set, or an electronic organizer which is portably used and can display information.
2. Description of the Related Art
As a device (to be referred to as a portable display device hereinafter) which is portably used and can display information, for example, a portable telephone set or a portable television receiver is known.
For example, in a portable telephone set, as shown in FIG. 27, an operation unit arranged in the main body (the main body of a portable image information display device) is operated to display the telephone number of a desired destination or other information on an information display unit.
Since the portable display device including the portable telephone set described above is formed in a small size to easily carry (bear) the portable display device, a display screen for displaying information (video image) such as a character is so small that a lot of information cannot be easily displayed at once.
In the conventional portable display device, as shown in FIG. 27, since the information display unit for displaying information is exposed, the information displayed on the display unit may be seen by the other.
In addition, when the information display unit receives strong external light out of doors, the contrast of the display screen may be degraded by reflection of the external light, and a user may be hard to see the display unit.
A user having poor sight cannot easily see information (video image) displayed on the small display screen.
Furthermore, in a portable television receiver cannot easily provide to a user a video image having power and the feeling of being at a live performance.
When the portable display device is operated, the device must be held with one hand, and an operation must be performed with the other hand. This is inconvenient when the user makes notes.
There is a method of increasing a display screen to make a video image legible. However, in this case, the device increases in size and weight, and the portability of the device is degraded. In addition, a power consumption required to display a video image increases, and the device cannot easily use for a long time.
As a device which is conveniently portable and legibly provides a lot of information, for example, a device which displays information with an virtual image is disclosed in Japanese Unexamined Patent Publication No. 2-86338.
However, development of a device which is further compact and is conveniently portable is desired.